Blood Flow Regulates Vasculature by Maintaining Collagen/elastin and MMP/TIMP ratio

Abstract

The structural and functional heterogeneity between blood vessels determine the degree of vascular remodeling. We hypothesized that the level of blood flow in different blood vessels causes structural and functional heterogeneity that determine the potential vascular remodeling. To test the hypothesis, the in vivo blood flow and the blood pressure in aorta, carotid, femoral arteries and femoral vein was measured in male Sprague‐Dawley rats (380–400gms). Aorta, femoral and carotid artery and the vena cava were isolated to measure the expression of MMP‐2, ‐9,‐12‐13 and TIMP‐1, ‐3, ‐4 by Western blot. Masson Trichrome and van Gieson stains were used for histological study. The results revealed that blood flow was higher in aorta and carotid artery. Further the expression of MMP‐9 and ‐13 were elevated in the carotid artery, as compared to other blood vessels while TIMP‐3 was increased in the aorta. There was a higher degree of basement membrane collagen in the femoral artery suggesting a low collagen/elastin ratio, while in the carotid artery higher level of elastin indicates a high collagen/elastin ratio. Additionally medial thickness and collagen/elastin ratio had a threshold in blood flow in range 0.6–2.5 ml/min, but increased robustly 2.7 ml/min blood flow, which was inverted by MMP/TIMP ratio. Based on these findings, we infer that blood flow plays pivotal role in maintaining vasculature.